FS-1015

FS-1015 is a secure telephony speech encoding standard developed by the United States Department of Defense and later by NATO. It is also known as LPC-10 and STANAG 4198.

The standard was finished 1984. The algorithm used is a linear predictive coding vocoder. The vocoder enables understandable speech, but the quality is very unnatural and synthetic.

The codec uses a bit rate of 2.4 kbit/s, requiring 20 MIPS of processing power, 2 kilobytes of RAM and features a frame size of 22.5 ms. Additionally, the codec requires a large lookahead of 90 ms.

Recently an improved version of the standard is introduced. With longer super frame structure and better quantizer the bit rate is reduced to 800 bit/s. [cite journal
quotes =
last = Xianglin
first = Wang
authorlink =
coauthors = C.-C. Jay Kuo
date =
year = 1998
month = May
title = An 800 bps VQ-based LPC voice coder
journal = The Journal of the Acoustical Society of America
volume = 103
issue = 5
pages = 2778
issn =
doi =
id =
url = http://link.aip.org/link/?JASMAN/103/2778/1
language =
format =
accessdate = 2007-03-24
laysummary =
laysource =
laydate =
quote = ]

External links

* [http://www.speech.cs.cmu.edu/comp.speech/Section3/Software/celp-3.2a.html CELP-3.2a and LPC-10]

References